1. Field
The embodiment relates to a light emitting device, and more particularly, to a lighting device for improving light emitting efficiency.
2. Background
Groups III-V nitride semiconductors have been extensively used as main materials for light emitting devices, such as a light emitting diode (LED) or a laser diode (LD), due to the physical and chemical characteristics thereof. In general, the groups III-V nitride semiconductors include a semiconductor material having a compositional formula of InxAlyGa1-x-yN (0≤x≤1, 0≤y≤1, and 0≤x+y≤1).
The LED is a semiconductor device, which transmits/receives signals by converting an electric signal into infrared ray or light using the characteristics of compound semiconductors. The LED is also used as a light source.
The LED or the LD using the nitride semiconductor material is mainly used for the light emitting device to provide the light. For instance, the LED or the LD is used as a light source for various products, such as a keypad light emitting part of a cellular phone, an electric signboard, and a lighting device.
A via hole type LED according to the related art is formed in a junction structure of a P type semiconductor and an N type semiconductor, but the N type electrode is designed to have a large area although holes (+) have a drift velocity less than that of electrons (−).
For this reason, the spreading of holes is decreased due to the bottleneck in the movement of holes, so that the light efficiency of the light emitting device may be deteriorated.